<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<style>
    .line {
        border-bottom: 1px #ff0000 solid;
        margin: 10px;
    }
    .line.hair {
        transform: scaleY(0.5);
    }
</style>
<body>
<!--通过transform: scaleY(0.5)实现-->
<div class="hair line"></div>
<div class="line"></div>
</body>
</html>
